An injection device of the aforementioned type is already known from European Patent No. EP 0 783 342 in the name of the DELAB company. This type of injection device includes a main body in two parts to which a hollow needle is fixed via a holding part. A rod is capable of sliding coaxially inside the needle and is stopped against an implant introduced into said needle. A secondary body is arranged coaxially inside the main body and surrounds the needle, such that the latter does not project prior to the injection. The secondary body includes one or several slots at different places on the length thereof, which join the two parts of the secondary body via radially extending connecting elements. The rod has a raised portion that is used as means for stopping the movement of said rod. The rod is connected to a piston, which, at the base thereof, includes a longitudinal hole. A guide element is secured to the piston and is arranged inside the main body so as to guide said piston and the rod.
One drawback of the injection device described above is that it includes a large number of parts. It is thus expensive to manufacture and difficult to assemble. Moreover, the relative movements of the constituent elements of the injection device in relation to each other are complex, which increases the risk of malfunction. Another drawback can be seen in the fact that the configuration of the injection device before and after injection is not the same, which makes this device particularly bulky and thus difficult to store.
It is an object of the present invention to overcome the aforementioned drawbacks in addition to others by providing an injection device which includes, in particular, a limited number of parts and which is thus less expensive to manufacture and easier to assemble.